don't forget lib64

In RedHat, if you do something like `pip install --install-option="--home=`pwd`/vendor-local" python-ldap` (same happens with `psycopg2`) they get installed in `vendor-local/lib64/python/...`. 

To be honest, I don't know why that happens on jenkins but not on my laptop. 

Anyway, adding this is harmless for those on sane systems that don't install into `lib64/python`. 

We needed this for socorro-crashstats so that psycopg2 and ldap could be used from the tarballs we build on jenkins. See [this code](https://github.com/mozilla/socorro-crashstats/blob/master/wsgi/socorro-crashstats.wsgi#L11-L13)